Lane-maze for preference testing in flies

Drosophila melanogaster is a candidate species to replace rodents in some neurobiological studies, encouraging attempts to develop behavioural tests for these flies. This study aimed to develop a behavioural test to simultaneously evaluate ethological (categorical) aspects of the motor and fluid intake activities, which may be used to assess sucrose preference in flies. For that, a lane-maze was 3D-printed to accommodate up to 14 individual flies in a single trial. Each lane had a capillary filled with 5% sucrose solution attached to one of the extremities. To validate a 5-min lane-maze test, male and female flies (adults, 5-6 days of age) underwent 0, 2, 8 or 20 h of food deprivation (FD, n=9-11/group) before testing. Duration of locomotion, immobility and grooming in the lane or capillary were scored from the video-recorded trials using EthoWatcher software. Minor effects of sex or FD were observed in the behaviours of flies. Independent of sex or FD, flies spent proportionally longer on the capillary than on the lane. Flies exhibited a significantly higher preference than expected for the capillary zone when food-deprived for 2h (males) or 20 h (females). Data suggest that short lane-maze test is a feasibly high throughput assessment of sucrose preference in flies, which may be sexually dimorphic as in other species studied so far.